Method of forming selective metal layer and method of forming capacitor and filling contact hole using the same

ABSTRACT

A selective metal layer formation method, a capacitor formation method using the same, and a method of forming an ohmic layer on a contact hole and filling the contact hole using the same, are provided. A sacrificial metal layer is selectively deposited on a conductive layer by supplying a sacrificial metal source gas which deposits selectively on a semiconductor substrate having an insulating film and the conductive layer. Sacrificial metal atoms and a halide are formed, and the sacrificial metal layer is replaced with a deposition metal layer such as titanium Ti or platinum Pt, by supplying a metal halide gas having a halogen coherence smaller than the halogen coherence of the metal atoms in the sacrificial metal layer. If such a process is used to form a capacitor lower electrode or form an ohmic layer on the bottom of a contact hole, a metal layer can be selectively formed at a temperature of 500° C. or lower.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing semiconductordevices, and more particularly, to a method of forming a selective metallayer and methods of forming a capacitor of a semiconductor device andfilling a contact hole using the same.

2. Description of the Related Art

As semiconductor devices become highly integrated and complicated, ametal layer must often be selectively formed while manufacturing thesemiconductor devices. In a process for manufacturing a capacitor of asemiconductor device, a lower electrode is formed using a metal insteadof polysilicon to obtain high capacitance, thereby achieving a metalinsulator silicon (MIS) or metal insulator metal (MIM) structure. Or, ina process for filling a contact hole, an ohmic layer is formed on thebottom of a small contact hole having a high aspect ratio. The above twoprocesses have many difficulties.

In the manufacturing process of the capacitor having the metallic lowerelectrode, it is very difficult to selectively deposit a metal layerwithout patterning the metal layer on a hemispherical grain (HSG)polysilicon lower electrode. At present, such technology is not known atall. Also, in order to use PZT(Pb(Zr,Ti)O₃) or BST((Ba,Sr)TiO₃), havinga Perovskite structure, as a high dielectric film of a capacitor, it ispreferable that platinium (Pt), which is not oxidized and has excellentleakage current properties, is used instead of an existing polysiliconelectrode, when a dielectric film is deposited. However, when a metallayer such as a platinum film is deposited by a blanket method ratherthan a selective method, etching is hard. That is, when the platinumfilm formed by the blanket method is dry-etched using chlorine (Cl₂) gasas an etchant, PtClx generated as a by-product of etching is anon-volatile conductive polymer. Thus, a process for removing the PtClxby wet etching must also be performed. In the wet etching process, toremove PtClx, part of a platinum lower electrode is also etched. It istherefore difficult to perform a repeatable process in a manufacturingprocess of a dynamic random access memory (DRAM) which requires finepatterning.

Also, the ohmic layer is formed on the bottom of the contact hole bydepositing a highly conductive metal having a high melting point, suchas titanium, by plasma enhanced chemical vapor deposition (PECVD) orsputtering. However, when sputtering is used to form the ohmic layer,step coverage is low. The PECVD is not suitable to apply to an actualprocess, since leakage current is increased by a high depositiontemperature of 600° C. or more and thus the electrical characteristicsof the semiconductor devices are deteriorated.

In addition, if the ohmic layer such as a titanium (Ti) layer is formedby sputtering, and a barrier layer, e.g., a titanium nitride (TiN)layer, is formed on the ohmic layer by chemical vapor deposition (CVD),the ohmic layer may be corroded and the interface between the ohmiclayer and the barrier layer may lift. If the barrier layer (TiN) isformed on a titanium (Ti) ohmic layer by sputtering, the interfacebetween the ohmic layer and the barrier layer does not lift. However,when a plug layer for filling the contact is formed using tungsten byCVD in a subsequent process, the lifting problem occurs.

Therefore, a method is required of selectively forming a metal layer ata temperature of 500° C. or lower where the electrical characteristicsof semiconductor devices are not degraded. However, at present, it isvery difficult to realize such a technique in the process of forming thelower electrode of the capacotor and forming the ohmic layer of thecontact hole.

SUMMARY OF THE INVENTION

To solve the above problems, it is an objective of the present inventionto provide a method of forming a selective metal layer, by which asacrificial metal layer is selectively deposited at a temperature of500° C. or lower. The sacrificial metal layer is replaced with adeposition metal layer by reacting the sacrificial metal layer with ametal halide gas having a smaller halogen coherence than a metallic atomof the sacrificial metal layer.

It is another objective of the present invention to provide a method offorming a capacitor of a semiconductor device using the selective metallayer formation method.

It is still another objective of the present invention to provide amethod of filling a contact hole using the selective metal layerformation method.

Accordingly, to achieve the first objective, in a selective metal layerformation method, a semiconductor substrate on which an insulating filmand a conductive layer are formed is loaded into a chamber, and a purgegas, e.g. a mixture of hydrogen and silane, is supplied to the chamber.A sacrificial metal layer is formed on only the conductive layer bysupplying to the chamber a sacrificial metal source gas which isdeposited selectively on the conductive layer. The sacrificial metalsource gas is preferably either dimethyl aluminum hydride (DMAH:(CH₃)₂AlH) or dimethyl ethylamine alane (DMEAA: (CH₃)₂C₂H₅N:AlH₃).Finally, the sacrificial metal layer is replaced with a deposition metallayer by supplying to the chamber a metal halide gas having a halogencoherence smaller than the halogen coherence of metal atoms in thesacrificial metal layer.

According to a preferred embodiment of the present invention, the purgegas is continuously supplied, or first supplied in a predeterminedamount to purge and periodically supplied in predetermined amounts afterthe sacrificial metal layer is formed and replaced with the depositionmetal layer. Here, it is suitable that the supply time and amount of apurge gas to be supplied after replacement of the deposition metal layerare greater than in other steps.

It is suitable that the insulating film is an oxide film (SiO₂) or acomplex film including the oxide film, and that the conductive layer isformed of silicon doped with impurities, or a metal containing material.

Preferably, the metal containing material for the conductive layer is arefractory metal, a refractory metal nitride, a refractory metalcarbide, a metal silicide, conductive Perovskite, a platinum-familymetal, a conductive platinum-family nitride, or a mixture of two or moreof the above materials. It is preferable that TiCl₄ is used as the metalhalide gas when the deposited metal is titanium. Also, it is preferablethat a gas obtained by dissolving platinic chloride (Cl₆H₆Pt) or PtCl₂in water (H₂O) or alcohol and vaporizing the dissolved Cl₆H₆Pt or PtCl₂is used as the metal halide gas when the deposited metal is platinum.

To achieve the second objective, in a method of forming a capacitor of asemiconductor device using a selective metal layer formation method, acontact hole exposing a source region of a semiconductor substrate isformed, by forming an insulating film such as an oxide film (SiO₂) or acomplex film including the oxide film on the semiconductor substrate andpatterning the insulating film. A conductive layer is formed ofpolysilicon doped with impurities, or a metal containing material,filling the contact hole and covering the insulating film. A conductivelayer pattern connected to the contact hole is formed by patterning orchemically mechanically polishing the conductive layer. Thesemiconductor substrate is introduced into a chamber, and a purge gas ofhydrogen (H₂) and silane (SiH₄), is supplied to the chamber. Asacrificial metal layer is formed on only the conductive layer, bysupplying to the chamber a sacrificial metal source gas which isdeposited selectively on the conductive layer. Here, the sacrificialmetal source gas is preferably either dimethyl aluminum hydride (DMAH:(CH₃)₂ALH) or dimethyl ethylamine alane (DMEAA: (CH₃)₂C₂H₅N:AlH₃). Then,the sacrificial metal layer is replaced with a deposition metal layer bysupplying to the chamber a metal halide gas having a halogen coherencesmaller than the halogen coherence of metal atoms in the sacrificialmetal layer. Finally, a dielectric film is formed on the depositionmetal layer, and an upper electrode is formed on the dielectric film.

According to a preferred embodiment of the present invention, the stepof forming a hemispherical grain on the surface of a conductive patterncan be performed after the conductive layer pattern is formed.

It is preferable that the purge gas is continuously supplied, or firstsupplied in a predetermined amount to purge and periodically supplied inpredetermined amounts after the sacrificial metal layer is formed andafter the sacrificial metal layer is replaced with the deposition metallayer. Here, it is proper that a purge gas supplied after the depositionmetal layer is replaced has a longer supply time and greater amount ofsupply than a purge gas supplied in other steps.

Also, according to the preferred embodiment of the present invention,the step of siliciding the deposition metal layer can be furthercomprised after the step of forming the deposition metal layer.

To achieve the third objective, in a method of filling a contact holeusing a selective metal layer formation method, an insulating film, suchas an oxide film (SiO₂) or a complex film including the oxide film, isformed on a semiconductor substrate. A contact hole exposing a lowerfilm of polysilicon doped with impurities, or a metal such as TiN, isformed by patterning the insulating film. The semiconductor substrate onwhich the contact hole is formed is introduced into a chamber, and apurge gas, preferably a mixture of hydrogen (H₂) and silane (SiH₄), issupplied to the chamber. A sacrificial metal layer is formed of aluminum(Al) on only the lower film by supplying to the chamber a sacrificialmetal source gas which is deposited selectively on the lower film. Here,the sacrificial metal source gas is either dimethyl aluminum hydride(DMAH: (CH₃)₂ALH) or dimethyl ethylamine alane (DMEAA:(CH₃)₂C₂H₅N:AlH₃). Then, the sacrificial metal layer is replaced with adeposition metal layer by supplying a metal halide gas having a halogencoherence smaller than the halogen coherence of metal atoms in thesacrificial metal layer, to the chamber. Finally, a conductive layerfilling the contact hole is formed.

According to the preferred embodiment of the present invention, thepurge gas is continuously supplied, or first supplied in a predeterminedamount to purge and periodically supplied in predetermined amounts afterthe sacrificial metal layer is formed and after the sacrificial metallayer is replaced with the deposition metal layer. Here, it is properthat a purge gas supplied after the deposited metal layer is replacedhas a longer supply time and greater amount of supply than a purge gassupplied in other steps.

Also, it is preferable to form a barrier layer, e.g., a TiN layer, on adeposition metal layer after the step of replacing the sacrificial metallayer with the deposition metal layer.

According to the present invention, in a process for manufacturingsemiconductor devices, a specific metal selectively formed at atemperature of 500° C. or lower is applied to the process for forming alower electrode of a capacitor, thereby forming a metallic lowerelectrode of a capacitor without serious process difficulty. Also, whenthe ohmic layer is formed on the bottom surface of the contact hole,property degradation or lifting of a thin film due to corrosion can beprevented, while simultaneously increasing step coverage.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objectives and advantages of the present invention will becomemore apparent by describing in detail preferred embodiments thereof withreference to the attached drawings in which:

FIG. 1 is a flowchart illustrating a process for forming a selectivemetal layer, according to the present invention;

FIGS. 2A and 2B are gas flow graphs of the process for forming aselective metal layer according to the present invention;

FIG. 3 is a flowchart illustrating a method of forming a capacitor usingthe selective metal layer formation process according to the presentinvention;

FIGS. 4A through 4F are cross-sectional views illustrating a method offorming a capacitor using the process for forming a selective metallayer, according to a first embodiment of the present invention;

FIGS. 5A through 5F are cross-sectional views illustrating a method offorming a capacitor using the process for forming a selective metallayer, according to a second embodiment of the present invention;

FIGS. 6A through 6C are cross-sectional views illustrating a method offorming a capacitor using the process for forming a selective metallayer, according to a third embodiment of the present invention;

FIG. 7 is a flowchart showing a method of filling a contact hole usingthe selective metal layer formation process according to the presentinvention; and

FIGS. 8A through 8E are cross-sectional views illustrating a contacthole filling method using the selective metal layer formation process,according to a fourth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Method of Forming a SelectiveMetal Layer

Referring to FIG. 1 illustrating a process for forming a selective metallayer, according to the present invention, first, a semiconductorsubstrate on which an insulating film and a conductive layer are formedis introduced into a chamber of a semiconductor manufacturing device, instep 100. Here, the insulating film is an oxide film (SiO₂) which doesnot absorb a metal deposited to form a selective metal layer, or acomplex film including the oxide film. The conductive layer is formed ofpolysilicon doped with impurities having hydrogen termination radical,on which aluminum Al can be easily and selectively deposited.Alternatively, the conductive layer is formed of a refractory metal, arefractory metal nitride, a refractory metal carbide, a metal silicide,conductive Perovskite, a platinum-family metal, a conductiveplatinum-family oxide, or a mixture of two or more of the abovematerials. The platinum-family metal can be Pt, Rh, Ru, Ir, Os or Pd,the conductive platinum family oxide can be PtOx, RhOx, RuOx, IrOx, OsOxor PdOx, and the conductive Perovskite can be CaRuO₃, SrRuO₃, BaRuO₃,(BaSr)RuO₃, CalrO₃, SrlrO₃, BalrO₃, or (La, Sr)CoO₃. Next, a purge gassuch as hydrogen H₂, silane SiH₄, nitrogen, argon, or a mixture of twoor more of the above gases is supplied to the chamber to purge theinside of the chamber, in step 110. Here, the purge gas can be suppliedby the following two methods. First, the purge gas can be continuouslysupplied in a predetermined amount from the beginning. Second, apredetermined mount of purge gas is supplied to the chamber aftersupplying a sacrificial metal source gas or a metal halide gas, to purgethe chamber, and a predetermined amount of purge gas can be periodicallysupplied after the steps 120 of depositing a sacrificial metal and afterthe step 140 of replacing the sacrificial metal layer with a depositionmetal layer.

A sacrificial metal layer made of aluminum (Al) is formed on the surfaceof the conductive layer by supplying to the chamber dimethyl aluminumhydride (DMAH: (CH₃)₂AlH) or dimethyl ethylamine alane (DMEAA:(CH₃)₂C₂H₅N:AlH₃) as a sacrificial metal source gas, in step 120. Thesacrificial metal layer is made of aluminum because aluminum willreadily combine with a halogen-family element such as Cl, Br, F or Iwith the highest Gibbs free energy. Moreover, various precursors foraluminum have already been developed. At the same time, Al halides haveGibbs free values that facilitates ready replacement of the Al metallayer as further described below. Precursors for the deposition ofaluminum include di-i-butylaluminum hydride ((C₄H₉)₂AlH),tri-i-butylauminum ((C₄H₉)₃Al), triethylanuminum ((C₂H₅)₂Al),trimethylaluminum ((CH₃)₃Al), trimethylamine (AlH₃N(CH₃)₃), dimethylaluminum hydride ((CH₃)₂AlH), and dimethyl ethylamine alane((CH₃)₂C₂H₅N:AlH₃). The dimethyl aluminum hydride ((CH₃)₂AlH)(hereinafter called ‘DMAH’) and dimethyl ethylamine alane((CH₃)₂C₂H₅N:AlH₃) (hereinafter called ‘DMEAA’) are not deposited on aninsulating film such as the oxide film (SiO₂) but they are depositedselectively on only a metal such as TiN or silicon which is doped withthe impurities of hydrogen (H₂) termination radical. That is, the DMAHand DMEAA are deposited not on the insulating film of the semiconductorsubstrate in the chamber but selectively on only the conductive layer.

Then, a purge gas is supplied to the chamber having the semiconductorsubstrate on which the sacrificial metal layer is selectively formed, topurge the sacrificial metal source gas from the chamber, in step 130.

Next, TiCl₄ is introduced into the chamber in step 140. The TiCl₄ isdecomposed and the Ti replaces the Al sacrificial layer to form a metallayer of Ti. Here, the metal in the metal halide gas has a weakerhalogen coherence than a metal atom of the sacrificial metal layer, sothat the metal atom of the sacrificial metal layer reacts with the metalhalide gas. That is, the Gibbs free energy of TiCl₄ is 678.3 kJ/mol at427° C. (700K), which is higher than that of most metal halides, whereasthe Gibbs free energy of AlCl₆ is 1121.9 kJ/mol which is higher thanthat of TiCl₄, so that the metal atoms of the sacrificial metal layerreact with the metal halide gas. Thus, aluminum atoms of the sacrificialmetal layer are separated from the surface of the conductive layer andreact with a chlorine (Cl) gas having a higher coherence, thus becomingAlCl_(x) of a gaseous state. Also, titanium (Ti) resolved from TiCl₄ isdeposited in the empty places where the aluminum atoms separate from thesurface of the conductive layer. When the metal halide gas having asmaller Gibbs free energy, i.e., the coherence between a sacrificialmetal and the halogen atom, is supplied into the chamber having thesemiconductor substrate on which the sacrificial metal is formed, ametal layer can be selectively formed. The deposition metal layer formedas described above can use titanium, tantalum, zirconium, hafnium,cobalt, molybdenum, tungsten, nickel or platinum.

Here, when the deposited metal is titanium, TiCl₄ is used as the metalhalide gas, and when the deposited metal is platinum, a gas obtained bymelting and vaporizing platinic chloride (Cl₆H₆Pt) or PtCl₂ in water(H₂O) or alcohol is used as the metal halide gas. Also, when thedeposited metal is cobalt, either cobalt chloride CoCl₂, cobalt fluorideCoF₂, or cobalt iodide CoI₂ is used as the metal halide gas. Here, sinceplatinic chloride (Cl₆H₆Pt) or PtCl₂, which is a metal halide containingplatinum, is solid, it must be used after being melted in a solvent andvaporized. Since platinum is inert compared with other metals, it has alower coherence with the halogen atom. Accordingly, when the platinumreacts with the sacrificial metal layer such as aluminum, it can beeasily deposited.

When the deposited metal is molybdenum, either bis(cyclopentadienyl)molybdenum dichloride (C₅H₅)₂MoCl₂,cyclopentadienylmolybdenum tetrachloride C₅H₅MoCl₄, molybdenum MoF₆,molybdenum fluoride MoCl₃/MoCl₅, or molybdenum iodide Mol₂ is used asthe metal halide gas. When the deposited metal is nickel, either[(C₆H₅)₂PCH₂CH₂CH₂P(C₆H₅)₂]NiCl₂ (1,2-bis(diphenylphosphineo)propanenickel), [(C₆H₅)₅C₅]₂NiBr₂ (bis(triphenylphosphin)nickel bromide),[(C₆H₅)₃P]₂NiCl₂ (bis(triphenylphosphin)nickel chloride), [Ni(NH₃)₆]Cl₂(hexaaminenickel chloride), [Ni(NH₃)₆]I₂ (Hexaamine iodide), NiBr/NiBr₂(nickel bromide), NiCl₂ (nickel chloride), NiF₂ (nickel fluoride), orNiI₂ (nickel iodide) is used as the metal halide gas. When the depositedmetal is tungsten, either bis(cyclopentadienyl)tungsten dichloride(C₅H₅)₂WCl₂, tungsten bromide WB/W₂B/W₂B₅, tungsten chloride WCl₄/WCl₆,or tungsten fluoride WF₆ is used as the metal halide gas.

For reference, Tables 1 through 5 show the Gibbs free energies of manymetal halide gases at an absolute temperature of 700K(427° C.).

TABLE 1 The Gibbs free energies of gaseous compounds containing Cl at427° C. gibbs free compound energy (kJ/mol) Al₂Cl₆ −1121.9 ThCl₄ −895.8UCl₅ −811.9 HfCL₄ −804.7 ZrCl₄ −777.6 LaCl₃ −708.9 PrCl₃ −706.9 In₂Cl₆−703.7 CeCl₃ −699.5 NdCl₃ −696.6 Be₂Cl₄ −692.6 TiCl₄ −678.3 GdCl₃ −674.3TbCl₃ −668.1 HoCl₃ −659.7 ErCl₃ −651.7 Cs₂Cl₂ −644.1 TmCl₃ −641.5 TaCl₅−636.6 HfCl₃ −626.7 EuCl₃ −621.6 YbCl₃ −621.5 K₂Cl₂ −609.8 Rb₂Cl₂ −607.6Li₂Cl₂ −597.8 SiCl₄ −569.6 AlCl₃ −550.1 Fe₂Cl₆ −526.8 BaCl₂ −524.3 SrCl₂−498.1 TaCl₄ −497.5 CaCl₂ −489.1 PbCl₄ −462.1 VaCl₄ −447.2 GeCl₄ −410.8MgCl₂ −407.8 Fe₂Cl₄ −406.5 GaCl₃ −388.6 BeCl₂ −373.1 BCl₃ −367.7 SiCl₃−365.7 SnCl₄ −362.3 InCl₃ −335.8 AlCl₂ −305.5 TaCl₃ −300.1 GeCl₃ −299.8MnCl₂ −286.4 WCl₅ −285.6 CSCl −276.7 ZnCl₂ −273.5 WCl₄ −267.6 Ti₂Cl₂−259.8 GaCl₂ −258.4 SbCl₅ −249.9 Cu₃Cl₃ −242.9 PCl₃ −242.3 FeCl₃ −240.6

TABLE 2 The Gibbs free energies of gaseous compounds containing iodine Iat 427° C. gibbs free compound energy (kJ/mol) ThI₄ −512 Al₂I₆ −510 K₂I₂−480 LaI₃ −457 PrI₃ −448 CeI₃ −442 NdI₃ −438 Li₂I₂ −427 ErI₃ −410 ZrI₄−409 HfI₄ −405 DyI₃ −402 TmI₃ −399 GdI₃ −388 BaI₂ −380 UI₄ −377 SrI₂−353 CaI₂ −338 TiI₄ −320 PbI₄ −266 MgI₂ −239 CuI −237 CsI −220 TaI₅ −202SiI₄ −150 HI −11.8

TABLE 3 The Gibbs free energies of gaseous compounds containing bromine(Br) at 427° C. gibbs free compound energy (kJ/mol) Al₂Br₆ −860 Mg₂Br₄−764 ThBr₄ −743 HfBr₄ −639 ZrBr₄ −627 LaBr₃ −621 CeBr₃ −616 PrBr₃ −612UBr₄ −602 NdBr₃ −598 HoBr₃ −567 ErBr₃ −566 TmBr₃ −563 TbBr₃ −559 DyBr₃−559 GdBr₃ −551 Li₂Br₂ −534 TiBr₄ −527 Na₂Br₂ −510 SrBr₂ −453 CaBr₂ −435PbBr₄ −428 TaBr₅ −424 EuBr₂ −413 SiBr₄ −387 Cu₃Br₃ −187 WBr₆ −139 HBr−58.6

TABLE 4 The Gibbs free energies of gaseous compounds containing fluorine(F) at 427° C. gibbs free compound energy (kJ/mol) Al₂F₆ −2439 UF₆ −1953TaF₅ −1687 ThF₄ −1687 Mg₂F₄ −1624 NbF₅ −1607 HfF₄ −1592 ZrF₄ −1587 S₂F₁₀−1581 SiF₄ −1515 WF₆ −1513 TiF₄ −1467 Li₃F₃ −1457 PrF₃ −1231 AsF₅ −1080CuF₂ −287.3 HF −277.1

TABLE 5 The Gibbs free energies of gaseous compounds containing platinum(Pt) at 427° C. gibbs free compound energy (kJ/mol) PtCl₂ −78.6 PtBr₂+29.2 PtI₄ +62.8 PtCl₃ −105.9 PtBr₃ +27.3 PtCl₄ −141.9 PtBr₄ −38.2

After the metal layer such as titanium, tantalum, zircium, hafnium,cobalt, molybdenum, tungsten, nickel or platinum is formed by areplacement method using the metal halide gas, a purge gas is suppliedto the chamber, in step 150. Here, the supply time and amount of purgegas are greater than in the step of forming the sacrificial metal layerand in other steps. Therefore, the metal halide gas such as TiCl_(x)adsorbed in a portion such as the insulating film, but not thesacrificial metal layer, is desorbed and purged.

FIGS. 2A and 2B are gas flow graphs of the selective metal layerformation process according to the present invention, wherein a Y axisdenotes the supply state of a gas, and a X axis denotes time. FIG. 2A isthe gas flow graph when a purge gas of hydrogen H₂ and silane SiH₄ issupplied periodically. FIG. 2B is the gas flow graph when the purge gasis continuously supplied from the beginning. The purge gas can behydrogen H₂, silane SiH₄, nitrogen N₂, argon Ar, or a mixture of two ormore of the above gases instead of a mixture of hydrogen H₂ and silaneSiH₄. When the purge gas is periodically supplied as shown in FIG. 2A, apurge gas 150 is supplied for a longer time and in a larger amount,right after a metal halide gas is supplied, to prevent the metal halidegas from being absorbed into the insulating film and to sufficientlydesorb the metal halide gas from the insulating film. To be morespecific, a purge gas 110 is first supplied, and a sacrificial metalsource gas 120 is then supplied to form a sacrificial metal layer. Whena purge gas is periodically supplied, a purge gas 130 is supplied to thechamber to purge the remaining sacrificial metal source gas. Also, ametal halide gas including a metal to be deposited is supplied toreplace a sacrificial metal layer with a deposition metal layer. At thistime, a compound gas of sacrificial aluminum, aluminum halides, andhalogen atoms remains in the chamber, and this is again purged to theoutside of the chamber by supplying the purge gas 150 to the chamber.This process is set as a cycle, and when this cycle is repeated, thethickness of a deposited metal can be easily controlled, and stepcoverage problems can be solved.

Method of Forming a Capacitor of a Semiconductor Device Using theSelective Metal Layer Formation Method

FIG. 3 is a flowchart illustrating a method of forming a capacitor usingthe selective metal layer formation process according to the presentinvention.

Referring to FIG. 3, a lower structure such as a transistor is formed,and an insulating film as an interlayer dielectric (ILD) is formed usingan oxide film or a complex film including the oxide film. A contact holeexposing a source area of a transistor is formed by performingphotolithography on the insulating film, in step 300. Optionally, anohmic layer and barrier layer can be formed using a material such astitanium (Ti) or titanium nitride (TiN), to improve conductivity betweenthe contact hole and a filling material and prevent diffusion, in step310. Then, a conductive layer covering the surface of the insulatingfilm is formed by filling the contact hole using a conductive materialfor a lower electrode, e.g., a metallic material such as TiN orpolysilicon doped with impurities. Here, it is preferable that theimpurities doped in the polysilicon have hydrogen termination radical toallow a sacrificial metal layer to be selectively formed in thesubsequent process. The conductive layer can be formed of a refractorymetal, a refractory metal nitride, a refractory carbide, a metalsilicide, conductive Perovskite, a platinum-family metal, a conductiveplatinum-family oxide, or a mixture of two or more of the abovematerials, instead of TiN.

Next, a conductive layer pattern for use as lower electrode connected tothe contact hole is formed by patterning the conductive layer, in step320. The conductive layer pattern can be formed after forming a pluglayer for filling only the inside of the contact hole, or bysimultaneously depositing and patterning a conductive layer for fillingthe inside of the contact hole. Here, the step 330 of forminghemispherical grains (HSG) on the conductive layer pattern can beoptionally performed to increase the surface area of the lowerelectrode. Then, the semiconductor substrate with the HSG is introducedinto a chamber of semiconductor manufacturing equipment, and a purge gasis supplied continuously or periodically as shown in FIGS. 2A and 2B, instep 340. A sacrificial metal source gas DMAH ((CH₃)₂ALH) orDMEAA((CH₃)₂C₂H₅N:AlH₃) is supplied to the chamber, and a sacrificialmetal layer of aluminum is formed selectively on only the conductivelayer, in step 350. A metal halide gas containing a metal to bedeposited, e.g., TiCl₄, platinic chloride (Cl₆H₆Pt), or PtCl₂, is meltedin water(H₂O) or alcohol and then vaporized, and the vapor is suppliedto form a deposition metal layer made of Ti or Pt using a replacementmethod, in step 360. Then, a silicide layer can be optionally formed byconducting a thermal treatment on the deposition metal layer, in step365. A nitride film can be optionally formed using ammonia plasma orrapid thermal nitridation (RTN), in step 370. An oxide film canoptionally be formed by performing a thermal treatment at an oxygenatmosphere, in step 375. Then, the nitride film and oxide film can beused as the dielectric film of a capacitor.

Here, when Ti is used as the first deposition metal layer, TiN is formedas the nitride film, and the selective metal layer formation processshown in FIG. 1 is repeated, thereby forming a second deposition metallayer made of platinum in step 373. The step 373 is optional.

Thereafter, the dielectric film is deposited on the resultant structure,in step 380. The dielectric film can be a complex film of an oxide filmand a nitride film, or can be formed of a monatomic metal oxide selectedfrom the group consisting of Ta₂O₅, TiO₂, ZrO₂, Al₂O₃, and Nb₂O₅, amonatomic metal nitride such as AlN, or a polyatomic metal oxideselected from the group consisting of SrTiO₃, PZT(Pb(Zr, Ti)O₃), andBST((Ba,Sr)TiO₃). Finally, an upper electrode is formed on thesemiconductor substrate on which the dielectric film is formed, usingpolysilicon or a metal such as TiN, TiAlN, or TiSiN, in step 390.

First Embodiment

FIGS. 4A through 4F are cross-sectional views illustrating a method offorming a capacitor using a selective metal layer formation processaccording to a first embodiment of the present invention.

Referring to FIG. 4A, a lower structure (not shown) such as a transistoris formed on a semiconductor substrate 400, and an oxide film or acomplex film including the oxide film is formed as an interlayerdielectric (ILD) 402 on the resultant structure. A contact hole 404exposing a source area of the transistor is formed by patterning the ILD402. Polysilicon which is doped with impurities and has hydrogentermination radical is deposited on the semiconductor substrate in whichthe contact hole 404 is formed, and the deposited polysilicon ispatterned, thus forming a lower electrode conductive layer pattern 406connected to the contact hole. The conductive layer pattern 406 can beformed of a refractory metal, a refractory metal nitride, a refractorycarbide, a metal silicide, conductive Perovskite, a platinum-familymetal, a conductive platinum-family oxide, or a mixture of two or moreof the above materials, instead of the pollysilicon doped withimpurities.

Referring to FIG. 4B, a deposition metal layer 408 such as Ti or Pt isformed on the resultant structure, using the selective metal layerdeposition method shown in FIG. 1. Here, a process for forming HSG canoptionally be performed on the conductive layer pattern 406 before thedeposition metal layer is formed, in order to increase the surface areaof the lower electrode of the capacitor. Thus, in the present invention,an HSG surface is formed, and the selective metal layer depositionaccording to the present invention is performed, whereby a capacitorhaving a metal insulator silicon (MIS) structure can be formed.

Referring to FIG. 4C, a nitride film 410 is formed on the semiconductorsubstrate on which the deposition metal layer 408 is formed, bynitridation or RTN using ammonia plasma (NH₃ plasma). The nitride film410 prevents oxidation at the interface between the lower electrode andthe dielectric film when the dielectric film is deposited in thesubsequent process which would degrades capacitance.

Referring to FIG. 4D, an oxide film 412, e.g., titanium oxide TiO₂, isformed by performing a thermal treatment in oxygen atmosphere on theresultant structure. The nitride film 410 and the oxide film 412 can beused as the dielectric film.

Referring to FIG. 4E, the dielectric film 414 is formed on the resultantstructure, using a monatomic metal oxide selected from the groupconsisting of Ta₂O₅, TiO₂, ZrO₂, Al₂O₃, and Nb₂O₅, a monatomic metalnitride such as AlN, or a polyatomic metal oxide selected from the groupconsisting of SrTiO₃, PZT(Pb(Zr, Ti) O₃), and BST((Ba, Sr)TiO₃).

Referring to FIG. 4F, an upper electrode 416 of polysilicon or a metalis formed on the semiconductor substrate on which the dielectric film414 is formed, thereby forming the capacitor of a semiconductor devicehaving a structure of metal insulator silicon (MIS) or metal insulatormetal (MIM).

If the capacitor of a semiconductor device is formed as described above,a photo process can be omitted since patterning is not required afterthe lower electrode is formed. Particularly, patterning on a lowerelectrode having HSG is not required, so that the lower electrode can beformed of a metal while avoiding many problems caused by etching.

Second Embodiment

FIGS. 5A through 5F are cross-sectional views illustrating a method offorming a capacitor using a selective metal layer formation processaccording to a second embodiment of the present invention.

Since processes shown in FIGS. 5A and 5B are the same as those in thefirst embodiment, the descriptions of these processes are omitted toavoid redundancy. Here, reference numerals correspond to those in thefirst embodiment for the sake of easy understanding.

Referring to FIG. 5C, a deposition metal layer 508, being the selectivemetal layer, is changed into a silicide layer 510 such as TiSix byperforming silicidation on the semiconductor substrate on which thedeposition metal layer 508 is formed.

Referring to FIG. 5D, a nitride film 512 is formed on the semiconductorsubstrate on which the silicide layer 510 is formed, using NH₃ plasma orby performing RTN.

Referring to FIG. 5E, a dielectric film 514 can be formed on thesemiconductor substrate on which the nitride film 510 is formed. Here,the dielectric film 514 can be a complex film of an oxide film and anitride film, or can be formed of a monatomic metal oxide selected fromthe group consisting of Ta₂O₅, TiO₂, ZrO₂, Al₂O₃, and Nb₂O₅, a monatomicmetal nitride such as AlN, or a polyatomic metal oxide selected from thegroup consisting of SrTiO₃, PZT(Pb(Zr, Ti)O₃), and BST((Ba, Sr) TiO₃).

Referring to FIG. 5F, an upper electrode 516 of polysilicon or a metalis formed on the semiconductor substrate on which the dielectric film isformed, thereby forming the capacitor of an MIS or MIM structure.

Third Embodiment

FIGS. 6A through 6C are cross-sectional views illustrating a method offorming a capacitor using a selective metal layer formation methodaccording to a third embodiment of the present invention.

The present embodiment can use the selective metal layer depositionprocess twice, to prevent a highly-resistive platinum silicide PtSixfrom forming when a platinum film is deposited selectively on acapacitor lower electrode.

Referring to FIG. 6A, a lower structure (not shown) such as a transistoris formed on a semiconductor substrate 600, and an inter layerdielectric (ILD) 602 is formed on the resultant structure, using anoxide film or a complex film including the oxide film. A contact holeexposing a source region of the transistor is formed on thesemiconductor substrate 600. A plug layer 604 for filling the contacthole is formed using polysilicon. Titanium nitride TiN being a capacitorlower electrode conductive layer, connected to the plug layer 604, isblanket-deposited by chemical vapor deposition (CVD) or physical vapordeposition. The capacitor lower electrode conductive layer is patternedto form a capacitor lower electrode conductive film pattern 606. Then, aplatinum film 608 is formed on the surface of the TiN conductive filmpattern 606, using the selective metal layer formation method shown inFIG. 1.

The capacitor lower electrode conductive film pattern 606 covered withthe platinum film 608 can also be formed by the following modifiedmethod. After the contact hole exposing the source region of thetransistor is formed, the plug layer 604 for filling the contact hole isformed of polysilicon doped with impurities having hydrogen terminationradical. Titanium is selectively deposited on the surface of the exposedplug layer 604 by the selective metal layer formation method of FIG. 1,thereby forming a planer type lower electrode conductive film pattern606. The Ti conductive film pattern 606 undergoes nitridation using NH₃plasma, or rapid thermal nitridation (RTN), to form TiN on the resultantstructure. Thereafter, the platinum film 608 is formed by the selectivemetal layer formation method of FIG. 1, thereby forming the capacitorlower electrode formed of the platinum film.

Referring to FIG. 6B, a dielectric film 610 is deposited on the platinumfilm 608. Here, the dielectric film 610 can be a complex film of anoxide film and a nitride film, or can be formed of a monatomic metaloxide selected from the group consisting of Ta₂O₅, TiO₂, ZrO₂, Al₂O₃,and Nb₂O₅, a monatomic metal nitride such as AlN, or a polyatomic metaloxide selected from the group consisting of SrTiO₃, PZT(Pb(Zr, Ti)O₃),and BST((Ba,Sr)TiO₃) .

Referring to FIG. 6C, a capacitor upper electrode 612 is formed on thesemiconductor substrate on which the dielectric film 610 is formed,using polysilicon or a metal such as platinum, thereby completing theformation of the capacitor of a semiconductor device using the selectivemetal layer formation method according to the third embodiment of thepresent invention.

Contact Hole Filling Method Using Selective Metal Layer Formation Method

FIG. 7 is a flowchart showing a method of filling a contact hole usingthe selective metal layer formation process according to the presentinvention.

Referring to FIG. 7, an insulating film is deposited on a semiconductorsubstrate on which a lower structure such as a transistor bit line isformed, using an interlayer dielectric (ILD), and a contact holeexposing a lower film is formed by patterning the ILD, in step 700.Here, the ILD is an oxide film or a complex film including the oxidefilm, and the lower film is formed of TiN, or polysilicon doped withimpurities having hydrogen termination. The lower film can be formed ofa refractory metal, a refractory metal nitride, a refractory carbide, ametal silicide, conductive Perovskite, a platinum-family metal, aconductive platinum-family oxide, or a mixture of two or more of theabove materials.

Here, the contact hole can be a capacitor lower electrode contact holedirectly connected to the semiconductor substrate, or a metal contacthole. Next, a deposition metal layer of a material such as titanium (Ti)is formed on the bottom of the contact hole, using the selective metallayer formation method shown in FIG. 1, in steps 710, 720 and 730. Thedeposition metal layer formed of a conductive material such as titanium(Ti) is used as an ohmic layer, in a process for filling the contacthole. Then, a barrier layer such as titanium nitride (TiN) is optionallyformed on the ohmic layer being the deposition metal layer, by RTN, ornitridation using NH₃ plasma, in step 740. A plug layer is formed ofaluminum (Al) and tungsten (W) on the barrier layer, in step 750. Aconductive layer connected to the plug layer is formed in step 760,thereby completing the filling of the contact hole. Here, withoutspecially forming the plug layer, a conductive layer for filling acontact hole can be formed directly on the barrier layer or ohmic layer.

In the step 740, the barrier layer can be formed and patterned by ablanket method of CVD or sputtering, instead of RTN or nitridation usingNH₃ plasma.

Fourth Embodiment

FIGS. 8A through 8E are cross-sectional views illustrating a method offilling a contact hole using a selective metal layer formation processaccording to a fourth embodiment of the present invention.

Referring to FIG. 8A, an insulating film 802, e.g., an oxide film or acomplex film including the oxide film, is formed on a semiconductorsubstrate 800, and a contact hole 804 exposing a lower film is formed bypatterning the insulating film 802. Here, the contact hole 804 can be acapacitor lower electrode contact hole connected to the semiconductorsubstrate, or a metal contact hole formed in a metal interconnectionprocess.

Referring to FIG. 8B, a deposition metal layer of a material such astitanium (Ti) is formed on the semiconductor substrate on which thecontact hole 804 is formed, using the selective metal layer formationmethod of FIG. 1. The deposition metal layer serves as an ohmic layer806 for improving the conductivity between the lower film and aconductive material for filling the contact hole, in the process forfilling the contact hole.

Referring to FIG. 8C, a barrier layer 808 for preventing diffusion ofimpurities, e.g., a titanium nitride (TiN) layer, is optionally formedon the semiconductor substrate on which the ohmic layer 806 isdeposited. The barrier layer can be formed by nitridation using NH₃plasma, RTN, or blanket deposition.

Referring to FIG. 8D, a conductive layer 810 for covering the surface ofthe semiconductor substrate while filling the contact hole is depositedon the semiconductor substrate on which the barrier layer 808 is formed,thereby completing the contact hole filling process using the selectivemetal layer formation method according to the fourth embodiment of thepresent invention.

FIG. 8E is a cross-sectional view of a modification of FIG. 8D. Here, aplug layer 812 is formed of tungsten (W) or aluminum (Al) on thesemiconductor substrate on which the barrier layer 808 is formed. Next,the plug layer 812 is removed except inside the contact hole, byetchback or chemical mechanical polishing (CMP). The conductive layer810 is then formed in contact with the plug layer 812.

Therefore, according to the present embodiment, a relatively thin ohmiclayer can be formed inside a contact hole having a high aspect ratiowithout problems such as lifting or corrosion, at a temperature of 500°C. or lower. This renders unnecessary a process for controlling thethickness of the ohmic layer, e.g., the etchback process.

According to the present invention as described above, since a metallayer of a material such as titanium (Ti) or platinum (Pt) isselectively formed of at a temperature of 500° C. or lower, a lowerelectrode can be easily formed of a metal instead of polysilicon in theprocess for forming a capacitor of a semiconductor device. Therefore,many problems generated in the prior art when the lower electrode isformed of titanium or platinum can be solved. Also, in the process forforming an ohmic layer on the bottom of a contact hole, the ohmic layerhaving an appropriate thickness is formed selectively at low temperatureon only the bottom of the contact hole, thus filling the contact holewhile preventing defects such as lifting or corrosion.

The present invention is not limited to the above embodiments, and it isapparent that various modifications within the technical spirit of thepresent invention may be effected by those skilled in the art.

What is claimed is:
 1. A method of forming a selective metal layer on asemiconductor substrate, the method comprising the steps of: forming aconductive layer on the substrate; forming an insulative layer over theconductive layer; etching a portion of the insulative layer and exposinga portion of the conductive layer; selectively forming a sacrificialmetal layer on the exposed portion of the conductive layer by exposingthe exposed portion of the conductive layer and the insulative layer toa sacrificial metal source gas which is deposited selectively on theconductive layer; and replacing the sacrificial metal layer with adeposition metal layer by supplying a metal halide gas having a halogencoherence smaller than the halogen coherence of metal atoms in thesacrificial metal layer.
 2. The method of claim 1, further comprisingthe step of supplying a purge gas before the sacrificial metal sourcegas is supplied.
 3. The method of claim 1, further comprising the stepsof: supplying a purge gas after the sacrificial metal layer is formed;and supplying a purge gas after the sacrificial metal layer is replacedwith the deposition metal layer.
 4. The method of claim 3, wherein adeposition metal layer having a desired thickness is formed by repeatingthe steps of: forming the sacrificial metal layer; supplying a purge gasafter the sacrificial metal layer is formed; replacing the sacrificialmetal layer with the deposition metal layer; and supplying a purge gasafter the sacrificial metal layer is replaced with the deposition metallayer.
 5. The method of claim 1, wherein the insulative layer comprisesan oxide.
 6. The method of claim 1, wherein the conductive layer isformed of a material selected from the group consisting of silicon dopedwith impurities and a metal containing material.
 7. The method of claim6, wherein the silicon doped with impurities has hydrogen terminationradical.
 8. The method of claim 6, wherein the metal containing materialfor the conductive layer is selected from the group consisting of arefractory metal, a refractory metal nitride, a refractory carbide, ametal silicide, conductive Perovskite, a platinum-family metal, aconductive platinum-family oxide, and a mixture of two or more of theabove materials.
 9. The method of claim 2, wherein the purge gas isselected from the group consisting of hydrogen (H₂), silane (SiH₄),nitrogen (N₂), argon (Ar)and a mixture of two or more of the abovegases.
 10. The method of claim 3, wherein the purge gas is selected fromthe group consisting of hydrogen (H₂), silane (SiH₄), nitrogen (N₂),argon (Ar), and a mixture of two or more the above gases.
 11. The methodof claim 9, wherein the purge gas is continuously supplied.
 12. Themethod of claim 10, wherein the purge gas is continuously supplied, orfirst supplied in a predetermined amount to purge and periodicallysupplied in predetermined amounts after the sacrificial metal layer isformed and after the sacrificial metal layer is replaced with thedeposition metal layer.
 13. A method of forming a capacitor of asemiconductor device using a selective metal layer formation method,comprising the steps of: (a) forming a source region on a semiconductorsubstrate; (b) forming an insulating film on a substrate and patterningthe insulating film to expose the source region on the substrate; (c)forming a conductive layer pattern on the insulating film and connectedto the contact hole; (c) selectively forming a sacrificial metal layeron the conductive layer, by exposing the conductive layer and theinsulating film to a sacrificial metal source gas which is depositedselectively on the conductive layer; (d) replacing the sacrificial metallayer with a deposition metal layer by supplying a metal halide gas, themetal having a halogen coherence smaller than the halogen coherence ofmetal atoms in the sacrificial metal layer; (e) forming a dielectricfilm on the deposition metal layer; and (f) forming an upper electrodeon the dielectric film.
 14. The method of claim 13, further comprisingthe step of supplying a purge gas before the step (c) of supplying thesacrificial metal source gas.
 15. The method of claim 14, wherein thepurge gas is continuously supplied, or first supplied in a predeterminedamount to purge and periodically supplied in predetermined amounts afterthe sacrificial metal layer is formed and after the sacrificial metallayer is replaced with the deposition metal layer.
 16. The method ofclaim 13, wherein the insulating film comprises an oxide.
 17. The methodof claim 13, wherein the conductive layer pattern in the step (b) isformed of a material selected from the group consisting of polysilicondoped with impurities and a metal containing material.
 18. The method ofclaim 13, further comprising the step of siliciding the deposition metallayer after the step (d) of replacing the sacrificial metal layer withthe deposition metal layer.
 19. The method of claim 17, wherein themetal containing material for the conductive layer pattern is selectedfrom the group consisting of a refractory metal, a refractory metalnitride, a refractory carbide, a metal silicide, conductive Perovskite,a platinum-family metal, a conductive platinum-family oxide, and amixture of two or more of the above materials.
 20. The method of claim13, wherein a deposition metal layer having a desired thickness isformed by repeating the step (c) of forming the sacrificial metal layerand the step (d) of replacing the sacrificial metal layer with thedeposition metal layer.
 21. The method of claim 13, wherein a depositionmetal layer having a desired thickness is formed by repeating the stepsof forming the sacrificial metal layer, of supplying a purge gas, ofreplacing the sacrificial metal layer with the deposition metal layer,and of supplying a purge gas.
 22. A method of filling a contact holeusing a selective metal layer formation method, comprising the steps of:(a) forming a first conductive layer on a semiconductor substrate; (b)forming an insulating film on the first conductive layer and forming acontact hole exposing a portion of the first conductive layer bypatterning the insulating film; (c) forming a sacrificial metal layer onthe exposed portion of the first conductive layer by supplying asacrificial metal source gas which is deposited selectively on theexposed portion of the first conductive layer; (d) replacing thesacrificial metal layer with a deposition metal layer by supplying ametal halide gas, the metal having a halogen coherence smaller than thehalogen coherence of metal atoms in the sacrificial metal layer; and (e)forming a second conductive layer filling the contact hole.
 23. Themethod of claim 22, wherein the insulating film in the step (a)comprises an oxide.
 24. The method of claim 22, wherein the lower filmin the step (a) is formed of a material selected from the groupconsisting of a refractory metal, a refractory metal nitride, arefractory metal carbide, and silicon doped with impurities havinghydrogen termination radical.
 25. The method of claim 22, furthercomprising the step of supplying a purge gas before the step (b) offorming the sacrificial metal layer.
 26. The method of claim 25, whereinthe purge gas is continuously supplied, or first supplied in apredetermined amount to purge and periodically supplied in predeterminedamounts after the sacrificial metal layer is formed and after thesacrificial metal layer is replaced with the deposition metal layer. 27.The method of claim 25, wherein the purge gas is selected from the groupconsisting of hydrogen (H₂), silane (SiH₄), nitrogen (N₂), argon (Ar),and a mixture of two or more of the above gases.
 28. The method of claim26, wherein the purge gas is selected from the group consisting ofhydrogen (H₂), silane (SiH₄), nitrogen (N₂), argon (Ar), and a mixtureof two or more of the above gases.
 29. The method of claim 22, wherein adeposition metal layer having a desired thickness is formed by repeatingthe steps (b) of forming the sacrificial metal layer and the step (c) ofreplacing the sacrificial metal layer with the deposition metal layer.30. The method of claim 22, wherein a deposition metal layer having adesired thickness is formed by repeating the step of forming thesacrificial metal layer, of supplying a purge gas, of replacing thesacrificial metal layer with the deposition metal layer, and ofsupplying a purge gas.
 31. A method of forming a selective metal layeron a semiconductor substrate, the method comprising the steps of:forming a conductive layer on the substrate; forming an insulative layerover the conductive layer; etching a portion of the insulative layer andexposing a portion of the conductive layer; selectively forming analuminum layer on the exposed portion of the conductive layer byexposing the exposed portion of the conductive layer and the insulativelayer to a sacrificial metal source gas containing aluminum; selectivelydepositing a sacrificial aluminum layer on the conductive layer; andreplacing the sacrificial aluminum layer with a deposition metal layerby supplying a metal halide gas having a halogen coherence smaller thanthe halogen coherence of metal atoms in the sacrificial metal layer. 32.A method of forming a selective metal layer on a semiconductorsubstrate, the method comprising the steps of: forming a conductivelayer on the substrate; forming an insulative layer over the conductivelayer; etching a portion of the insulative layer and exposing a portionof the conductive layer; selectively forming a sacrificial metal layeron the exposed portion of the conductive layer by exposing the exposedportion of the conductive layer and the insulative layer to asacrificial metal source gas containing aluminum; selectively depositinga sacrificial aluminum layer on the conductive layer; and replacing thesacrificial aluminum layer with a deposition metal layer by supplying ametal halide gas having a halogen coherence smaller than the halogencoherence of metal atoms in the sacrificial metal layer.